Packet data communication networks that are accessible to the public are subject to intrusion and disruption by predatory elements, such as hackers. By targeting a few critical nodes with a destructive virus or worm, it is possible to take down an entire network. Prior-art routers have done little more than reading header information and forwarding each data packet to the destination indicated in the associated header. This has provided no protection to destination devices, including computers and other routers that might be harmed by the user data carried by the data packet.
Thus, what is needed is a method and apparatus for providing node security in a router of a packet network. Preferably, the method and apparatus will be able to detect and eliminate potentially harmful data packets soon after they enter the network, and before they can reach destinations where they can produce widespread harm.